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Experimental

loki.source.kubernetes

EXPERIMENTAL: This is an experimental component. Experimental components are subject to frequent breaking changes, and may be removed with no equivalent replacement.

loki.source.kubernetes tails logs from Kubernetes containers using the Kubernetes API. It has the following benefits over loki.source.file:

  • It works without a privileged container.
  • It works without a root user.
  • It works without needing access to the filesystem of the Kubernetes node.
  • It doesn’t require a DaemonSet to collect logs, so one Grafana Agent could collect logs for the whole cluster.

NOTE: Because loki.source.kubernetes uses the Kubernetes API to tail logs, it uses more network traffic and CPU consumption of Kubelets than loki.source.file.

Multiple loki.source.kubernetes components can be specified by giving them different labels.

Usage

river
loki.source.kubernetes "LABEL" {
  targets    = TARGET_LIST
  forward_to = RECEIVER_LIST
}

Arguments

The component starts a new reader for each of the given targets and fans out log entries to the list of receivers passed in forward_to.

loki.source.kubernetes supports the following arguments:

NameTypeDescriptionDefaultRequired
targetslist(map(string))List of files to read from.yes
forward_tolist(LogsReceiver)List of receivers to send log entries to.yes

Each target in targets must have the following labels:

  • __meta_kubernetes_namespace or __pod_namespace__ to specify the namespace of the pod to tail.
  • __meta_kubernetes_pod_name or __pod_name__ to specify the name of the pod to tail.
  • __meta_kubernetes_pod_container_name or __pod_container_name__ to specify the container within the pod to tail.
  • __meta_kubernetes_pod_uid or __pod_uid__ to specify the UID of the pod to tail.

By default, all of these labels are present when the output discovery.kubernetes is used.

A log tailer is started for each unique target in targets. Log tailers will reconnect with exponential backoff to Kubernetes if the log stream returns before the container has permanently terminated.

Blocks

The following blocks are supported inside the definition of loki.source.kubernetes:

HierarchyBlockDescriptionRequired
clientclientConfigures Kubernetes client used to tail logs.no
client > basic_authbasic_authConfigure basic_auth for authenticating to the endpoint.no
client > authorizationauthorizationConfigure generic authorization to the endpoint.no
client > oauth2oauth2Configure OAuth2 for authenticating to the endpoint.no
client > oauth2 > tls_configtls_configConfigure TLS settings for connecting to the endpoint.no
client > tls_configtls_configConfigure TLS settings for connecting to the endpoint.no
clusteringclusteringConfigure the component for when Grafana Agent Flow is running in clustered mode.no

The > symbol indicates deeper levels of nesting. For example, client > basic_auth refers to a basic_auth block defined inside a client block.

client block

The client block configures the Kubernetes client used to tail logs from containers. If the client block isn’t provided, the default in-cluster configuration with the service account of the running Grafana Agent pod is used.

The following arguments are supported:

NameTypeDescriptionDefaultRequired
api_serverstringURL of the Kubernetes API server.no
kubeconfig_filestringPath of the kubeconfig file to use for connecting to Kubernetes.no
bearer_tokensecretBearer token to authenticate with.no
bearer_token_filestringFile containing a bearer token to authenticate with.no
proxy_urlstringHTTP proxy to proxy requests through.no
follow_redirectsboolWhether redirects returned by the server should be followed.trueno
enable_http2boolWhether HTTP2 is supported for requests.trueno

At most one of the following can be provided:

basic_auth block

NameTypeDescriptionDefaultRequired
password_filestringFile containing the basic auth password.no
passwordsecretBasic auth password.no
usernamestringBasic auth username.no

password and password_file are mutually exclusive, and only one can be provided inside a basic_auth block.

authorization block

NameTypeDescriptionDefaultRequired
credentials_filestringFile containing the secret value.no
credentialssecretSecret value.no
typestringAuthorization type, for example, “Bearer”.no

credential and credentials_file are mutually exclusive, and only one can be provided inside an authorization block.

oauth2 block

NameTypeDescriptionDefaultRequired
client_idstringOAuth2 client ID.no
client_secret_filestringFile containing the OAuth2 client secret.no
client_secretsecretOAuth2 client secret.no
endpoint_paramsmap(string)Optional parameters to append to the token URL.no
proxy_urlstringOptional proxy URL for OAuth2 requests.no
scopeslist(string)List of scopes to authenticate with.no
token_urlstringURL to fetch the token from.no

client_secret and client_secret_file are mutually exclusive, and only one can be provided inside an oauth2 block.

The oauth2 block may also contain a separate tls_config sub-block.

tls_config block

NameTypeDescriptionDefaultRequired
ca_pemstringCA PEM-encoded text to validate the server with.no
ca_filestringCA certificate to validate the server with.no
cert_pemstringCertificate PEM-encoded text for client authentication.no
cert_filestringCertificate file for client authentication.no
insecure_skip_verifyboolDisables validation of the server certificate.no
key_filestringKey file for client authentication.no
key_pemsecretKey PEM-encoded text for client authentication.no
min_versionstringMinimum acceptable TLS version.no
server_namestringServerName extension to indicate the name of the server.no

The following pairs of arguments are mutually exclusive and can’t both be set simultaneously:

  • ca_pem and ca_file
  • cert_pem and cert_file
  • key_pem and key_file

When configuring client authentication, both the client certificate (using cert_pem or cert_file) and the client key (using key_pem or key_file) must be provided.

When min_version is not provided, the minimum acceptable TLS version is inherited from Go’s default minimum version, TLS 1.2. If min_version is provided, it must be set to one of the following strings:

  • "TLS10" (TLS 1.0)
  • "TLS11" (TLS 1.1)
  • "TLS12" (TLS 1.2)
  • "TLS13" (TLS 1.3)

clustering (beta)

NameTypeDescriptionDefaultRequired
enabledboolDistribute log collection with other cluster nodes.yes

When Grafana Agent is using clustering, and enabled is set to true, then this loki.source.kubernetes component instance opts-in to participating in the cluster to distribute the load of log collection between all cluster nodes.

If Grafana Agent is not running in clustered mode, then the block is a no-op and loki.source.kubernetes collects logs from every target it receives in its arguments.

Exported fields

loki.source.kubernetes does not export any fields.

Component health

loki.source.kubernetes is only reported as unhealthy if given an invalid configuration.

Debug information

loki.source.kubernetes exposes some target-level debug information per target:

  • The labels associated with the target.
  • The full set of labels which were found during service discovery.
  • The most recent time a log line was read and forwarded to the next components in the pipeline.
  • The most recent error from tailing, if any.

Debug metrics

loki.source.kubernetes does not expose any component-specific debug metrics.

Example

This example collects logs from all Kubernetes pods and forwards them to a loki.write component so they are written to Loki.

river
discovery.kubernetes "pods" {
  role = "pod"
}

loki.source.kubernetes "pods" {
  targets    = discovery.kubernetes.pods.targets
  forward_to = [loki.write.local.receiver]
}

loki.write "local" {
  endpoint {
    url = env("LOKI_URL")
  }
}

Compatible components

loki.source.kubernetes can accept arguments from the following components:

Note

Connecting some components may not be sensible or components may require further configuration to make the connection work correctly. Refer to the linked documentation for more details.